Thermal protective device for electric circuits



- 1,6 July 26,1927. T Q DREYER v 36,953

Y THERMAL PROTECTIVE DEVICE FOR ELECTRIC CIRCUITS Filed Oct. 17. 1925 2 Shoots-Sheet 1 Fig.1.

Jnventor: OZ'ZO jre yer' 3 9 a,

July 26, 1927. 1,636,953

o. DREYER THERMAL rnowsbnvs DEVICE FOR ELECTRIC cmcurrs Filed Oct. 17. 1925 2 Sheets-Sheet 2 Jnventor; .0520 reye Ffforney "-what weaker than the former.

by the coils 2' and 3 the latter being'some- I The upper armature acts, through a shackle 14, upon the leverwhich turns on the pin 16 and Y which is held up by the head 17 of the rod 5 which is supported by the soldered joint,

said lever bein held locked by said rod as long as the so dered joint is not softened. The lower armature 13 acts in a similar manner, by means of the shackle 18, on the lever 19 which turns on the pin 20, and which is held locked b means of the head-21 on the rod held by t e lower soldered joint. Lever 19 is' additionally locked by means of a rop or detent'22 which is-fixed on the sha 24 and which is rovided with a nose 23. On the shaft 24 w ich carries the is fastened,- as can be seen in ig. 2, a lever 27 with which a rod is connected by means of the pin-26, which rod is heldin its raised position by the action of a spring 28. The

' a lateral projection 29 on the shac e 14' ead 3001 this rod 25 is situated 0 posite which is influenced by the upper releasing device or armature and can consequently be presseddownwa-rds when the releasing armature comes into action so that the nose 23 turns in the direction of the arrow and unlocks the lower releasing armature. v

In order -to retard the movement of the armature 12 by its magnet coil a brake 0r retarding device is provided. The latter :cylinder is provided in t upper. armature 12 when it comes into action v.may if desired act also on signa-l contacts,

' follows while the lower armature 13 brings together the contacts 34, 35 for closing a circuit the release of'themain switchfsuch circuit and switch not being illustrated, and'which may be of any "well-known type for a maximum, e. g., com lete cut-out action.

The in e of operation of the device is as Since a complete cut-ofi action is intended mil in the case-of direct short-circuits, and

un er'other dangerous conditions theprotective device illustrated never comes into lay for acompl'ete cut-ofl' action until ado its temperatln'e-limit is 'reached.'- Consequently overloads-are possible up to adetermined maximum and of a'duration up to the time required for the unsoldering of the upper soldered joint. At the instant this joint is unsoldered the coil 2 comes into 'actionand attracts the armature 12.,- This attraction takes place after a 'determined'period, inv fact after such a time interval as is deterv 1f the solder aocidentl hardens while the minedby the adjustment of the oil ump When the armature comes to rest, t at 15,

prop 22, there higher current.

the-device readily 1,eae,ese

when the retard period ends, a signal in ad vance canbe given as desired b this armature, so that attention may be rawn to the existing state of danger without a switching off action occurring By the movement of the armature 12 pressure is exerted on the rod 25 so that the lever 22 is so moved in the direction of the arrow that the nose 23 releases the end of the lever- 19. The armature 13 is nevertheless still prevented from bein drawn upward by magnet coil 3 until the lower soldered joint also softens, which joint possesses a somewhat higher melting point than the upper soldered joint,

and not until then is it possible for the armature 13 to be attracted by the coil 3, which can only occur at a definite strength of current, suitably below the determined maximum load current. Current to the motor may, therefore, still flow, notwithstanding the fact that both soldered joints having'become sensitive to allow any further permanent-load without cut-off as long as this limiting value of the current, for exam 1e, 10%

below the normal permanent loa determined for'the lowerarmature 13 or the coil- 3, is not Taxceeded. If this value is momentarily exceeded, the armature 13 is drawn upward by magnet 3 and contact is made between 34 and 33 and consequently the maximum cut-out switches off the current. All the coils of ,the relay thus also become dead and both armatures pass back into their normal position's shown in Fi 1. The relay remains active as long as t e two soldered joints are soft, that is, as long as there is a danger of the tem%rature of the motor becoming too high. condition it is still pmble to start under load the motor connected in the circuit, provided that'the starting operation does not r uire moretime than is de ay determined by the oi pump retarder. Thus if intheposition represented in Fig. 1 the motor is started again after having been switched in, the current being indriven the iston of the oil pump to the limit of its ownward movement. This 1%- quires a definite time and if the starting operation is completed in this time and the current ha's'returned to about 10% below the normal load, the armature 13, does not switch off the current since the coil 3 acts only at a rmitted by the As is evident from the above the mode of parts are out of, norms position, .the apps ratus cannot fail towork since in thiscase it does notremain non-sensitive but is re'nsible to .utilize to an extent: hitherto unat- Itained electrical machines, v. lar motors, by prov dingseflective protection and in particuagainst excessive heating whileallowingthe possibility of overloadnecessary in pract ce both' on starting and also during running.

[examples represented since other constructional forms are possible. In particular, the device is not only capable of being used as shown for continuous current but with suitable modifications also for other kinds of current. Further, the amounts given for the regulation of the current, as for example 90% of the normal permanent load current movement of said armature thereof.

; armature, and means varying 40 are not to be used for every case bu'tif .de- 1 sired are to be so varied that the additional heatings resulting in practice in consequence 'of. load shocks are balanced by a s uitablereduction of the current strength.

I claim v 1. A thermoelectric controller for electric circuits 'embodyin armature influence thereby, thermally controlled means for locking and releasing-said armature, and a retarder v govermng the upon the release 2. A thermoelectric controller-for electric circuits embodying an electro-magnet, an armature influenced thereby, thermally controlled means for locking and releasing said in accordance with lapse of time for controlling the movement of said armature when relased and under the attractive influence of the electromagnet.

3. A thermoelectric controller for electric circuits comprising a. pair of electro-magnetic coils, armatures influenced thereby, thermally controlled means'for locking the armature of at least one of said electromagnetic coils'from action and releasing the same so as to be influenced by said'coil, and means for holding from action the armature of the other electromagnetic coil, said means being releasable bythe movement of said thermally controlled armature upon there-- lease thereof.

4. A thermoelectric;controller for electric circuits embodyingfin electrosmagnet, an armature, influenced-thereby, thermally :controlled means for locking said armature from action and releasing the same for action at a predetermined-temperature, "and a cushioned brake device for governing the action of the released armature.

5. A'thermoelectriccontroller com risin a pair of comparatively strong and wea 'lioldin erned by the thermally controlled means oparmatures from movement an electro-rmagnet, an'

nets operative electro-magnetic coils, armatures influenced thereby, thermally controlled means for lock-- ing said armatures from action and respectively releasing the same so as to be attractedby their coils at relatively dilierent temperatures, and amechanical locking device for the electro-magnet armature j goverative at the lower temperature,

said mechanical locking device being releasable by the movement of the other armature upon 7 the release thereot. Of course the invention is not limited to the 6. A thermoelectric controller for electric circuits embodying a pair of electro-magsame for action respectively at predetemined diflerent temperatures.

7 A thermoelectriccontroller for electric circuits-embodying a pair of 'electro-mag nets operative at different current strengths, armatures respectively influenced thereby, thermally controlledmeans for locking said and for respectively releasing the same for action at predetermined different temperatures, and a retarder governing .the movement of the arma-- ture released by the thermally controlled means influenced at the lower temperature.

' 8. A thermoelectric controller for electric circuits comprising a. pair of electro-magat difi'erent currentstrengths, arm atures respectively influenced thereby, thermally controlled means for locking said leasing the-same for action at predetermined different temperatures, a retarder governing the movement'of the armature released for action at the lower temperature,"and a looking device for holding from action the armatureqeleased at the higher temperature, said locking device being automatically releasable by'the movement ofz'the armature releasedat the lower temperature upon the release thereof and its attraction by its electromagnet. Y

. 10. A thermoelectric controller for elec-' tric circuits vcomprising a pair of electromagnets armatures respectively influenced thereby, thermally controlled'devices for armatures from action and respectively releas ng the same for action at predetermined and a locking device said locklocking the armatures from action and respectively releasin the same-for action at predetermined di erent temperatures, and resetting means associated with the thermally controlled locking and releasing devices for retracting the armatures when their clectromagnets are demagnetized.

magnetic coils, armatures influenced thereby,

thermally controlled means for locking the armature of at least one of said electromagnetic coils from action and releasing the same so as to be influenced by its coil,- a

- mechanical locking device for holding from action the armature of "the other electromagnetic coil. said mechanical locking device being releasable by the movement of said thermally controlled armature upon the release thereof, and a retarder governing the action of one of said armatures. v

13. A thermoelectric controller for electric circuits comprising a pair of electromagnetic-coils, armatures influenced thereby, thermally controlled means for locking the armature of at least one of said electromagnetic coils from action and releasing the same so as to be attracted by-itscoil, are'tarder governing the action of said the-rmally controlled. armature, and a mechanical locking device for holding from action the armature of the other. electro-magnetic coil, said mechanical locking. device being releasable by the movement of said thermally ILA thermoelectric controller for electric circuits comprising a pairv of comparatively strong and weak electro-magnetlc coils, armatures influenced thereby, thermallycontrolled means for-locking at least the armature of said comparatively strong electro-m'a gnetic coil from action and releasing the same so as to be attracted b its coil, a retarder governing the action 10 the:

armature of said comparatively strong coil, and a mechanical locking device for holding controlled armature upon the release thereof from action the'armature of said comparatively weak coil, said mechaniul locking-device being releasable by the movement of the armature of said comparatively strong coil upon the release thereof.

15. A thermoelectric controller for electric circuits comprising a pair of electromagnetic coils, armatures influenced there by, thermally controlled means for locking said armatures from,action and respectively releasm the same for action'at predetermined dlflerent temperatures, a retarder governing the circuit controlling actions of the armature released for action'atthe lower temperature, and a locking device for holding from action the'armature released'at the higher-temperature, said locking device'being' automaticall releasable by the armature released at the release thereof. a

16. A thermoelectric controller for electric circuits comprising a pair ofcomparatively strong and weak electro-magnetic ower temperature upon the coils, armatures influenced thereby, thermally controlld means for locking the armatures of said coils from action and respectively releasing the same. for action at predetermined different temperatures, vizi the armature of the comparatively strong .coil

at a predetermined low temperature-and the pera-ture, a retarder governing the action of the armature of said comparatively 'st-rong'coil, and a mechanical lOCkIIlg device 'for holding from action the armature ofsaid comparatively 'weak coil, said locking device being automatically releasable by the armature ofsaid comparativelystrong coil upon the releasethereofp 17. A thermoelectric controller for electric circuitscompri'sing a pair'of relatively strong andfweak electro-magnetic coils, armatures respectively influenced thereby, and thermally controlled means for locking from [action thearmature of at least the weaker electro-magnetic coil and releasing the same so as to be influenced by 'itsycoil. i

'18. A thermoelectric controller for electriccircuits comprising apair of relatively strong-midweek electro-magnetic coils. armatures respectively influenced thereby,

thermall controlled means for locking from action'g-st eyarmature of at least the weaker electro-magneticcoil and releasing the same so as to be influenced by its coil, and lockmeans for the armature of; the stronger :5 adapted to be released by the movement of thearma'ture of the wea er coil,

In testimony whereof Ia in Si nature. a OTTO Dl lE ER.

90 armature of the other coil at a higher tem- 

